1. Field of the Invention
The present invention relates to an image protecting film used as a transparent film to be laminated on an image formed on photographic paper so as to protect the surface of the image.
2. Related Background Art
Conventionally, a transparent film is laminated on an image formed on photographic paper, particularly, an image formed by a sublimation type heat-transfer system using a subliming or thermal diffusing dye, in order to protect the surface, prevent discoloration and impart sebum resistance thereto.
A method of laminating a transparent film has been proposed in which a laminated film having a substrate and a laminated layer comprising a thermoplastic resin and formed on the substrate is partly heated and pressed so that only the heated portion of the laminated layer can be transferred to photographic paper, i.e., a method using a transfer type image protecting film has been proposed (Japanese Patent Laid-Open Nos. 60-204397, 59-85793 and 59-76298). The use of such a transfer type image protecting film can prevent curling of photographic paper to which the transparent film is laminated, and improve the sebum resistance to the sebum of hands and the plasticizer resistance to the plasticizers contained in vinyl chloride products such as wallpaper, floor mats, tablecloths, etc.
In order to prevent discoloration of an image due to ultraviolet rays, an attempt has been made to contain an ultraviolet absorber in a laminated layer of such a transfer type image protecting film to be transferred onto the image.
However, some ultraviolet absorbers speed up discoloration of a dye if coexisting with the dye. When a laminated layer containing an ultraviolet absorber is transferred onto an image, and when the dye which forms the image and the ultraviolet absorber are transferred into the same layer or adjacent layers, there is the problem of promoting discoloration of the image. Therefore, when an ultraviolet absorber is contained in a laminated layer to be transferred onto an image, the types and amounts of ultraviolet absorbers which can be used are, of course, limited, thereby making impossible to impart the practically effective ability to absorb ultraviolet rays to the laminated layer.